I have a docker container as part of docker-compose that should reach other containers but as well a server running in my local network.
(the docker container is a monitoring service)
I know that in order to reach the local LAN I should configure the network mode to “host”, is that correct? In that case am I still able to reach the other containers running in the default bridge network?
No, that has nothing to do with that.
No, using network_mode host makes it more complicated to also reach other containers on the same Docker host.
Why not ask /r/Docker and read the Docker documentation?